Field of the Invention
The present invention concerns wireless communications, and more specifically, to a method and apparatus of transmitting channel change information.
Related Art
Machine-to-machine (M2M) systems recently draw attention as next-generation communication technology and new standards for supporting the same are now being establishment in IEEE 802.11 WLAN. An M2M system means a network where not humans but machines perform communication to exchange information. Temperature sensors, moisture sensors, cameras, TVs or other home appliances, factory processing machines, vehicles, and other large-size machines may be M2M elements. Recently, as smart grid, e-Health, ubiquitous and other various communication services appear, M2M techniques are being utilized to support such services. The M2M system has the following features.
1) Many stations: M2M assumes a great number of stations unlike existing networks because not only an individual's machine but also sensors installed in home or business should be taken into account. Accordingly, a large number of stations may be linked to a single AP.
2) Low traffic load per station: since an M2M terminal collects and reports ambient information in its traffic pattern, it need not often send information and the amount of information to be sent is relatively small.
3) Uplink-centered: M2M has a structure of primarily receiving commands on downlink, taking an action, and then reporting resultant data on uplink. Major data is usually transmitted on uplink, and thus, M2M is uplink-centered.
4) Long life-span station: an M2M terminal is primarily battery-powered, and is in many cases difficult for a user to recharge often. Accordingly, battery consumption needs to be minimized, ensuring long lifespan.
5) Automatic restoring function: an M2M terminal is hard for a human to directly manipulate and thus it requires a self-restoring function,